Nanoparticles in food can alter the behavior of gut bacteria


gut bacteria viewed under microscope

By Catharine Paddock PhD  
Fact checked by Jasmin Collier
New
research on nanoparticles in food has yielded fresh insights about their impact
on gut bacteria.
Researchers
from the University Medical Center of Mainz in Germany and colleagues from
other centers in Germany, Austria, and the United States have discovered that
the ultra-tiny particles can bind to gut bacteria.
In
a study paper about their work — which now appears in the journal npj Science
of Food — the authors explain how attachment to nanoparticles can alter the
life cycle of gut bacteria and their interactions with their host’s body.
The
results should be useful to both medicine and the food industry. They could,
for instance, lead to research into the use of nanoparticles in probiotics.
One
example of this is the scientists’ observation that synthetic nanoparticles can
prevent infection by Helicobacter pylori.
H.
pylori is a bacterium that grows in the lining of the human stomach. It is of
keen interest to many scientists due to its complex relationship with cancer.
“Prior
to our studies,” says study senior author Roland H. Stauber, a professor
in the Department of Otolaryngology, Head, and Neck Surgery at Mainz University
Medical Center, “nobody really looked whether and how nano-additives
directly influence the gastrointestinal flora.”
Use of nanoparticles is growing rapidly
Nanotechnology
manipulates materials at the nanometer scale, which is around the same scale as
that of atoms and molecules. One nanometer is 1 billionth of a meter, which
means that there are 25,400,000 of them in 1 inch.
In
their study background, Prof. Stauber and colleagues describe how the use of
nanoparticles is rising rapidly in many fields. These range from medicine and
agriculture to the manufacture of personal care products and food processing.
The
food industry, for example, uses synthetic nanoparticles to lighten and color
food, deliver nutrients, and prevent infection.
All
of these can enter the human gut “as part of nano-enabled foods and
beverages,” report the study authors.
Nanoparticles
are of interest not just because they are very small, but also because the
materials that comprise them have unique properties at the nanoscale.
Compared
with bigger particles derived from the same materials, nanoparticles have a
much larger surface area relative to their size, have “greater Brownian
motion,” and are able to cross biological barriers. These barriers include
the mucus layer that lines tissues such as the gut.
For
these reasons, their fate in the human gut is likely to differ greatly from
that of larger-scale counterparts derived from the same materials.
According
to the study authors, “It is, therefore, important to ensure that any
nano-enabled food ingredients are safe for application in foods.”
The human gut and its microbiome
The
human gut, or gastrointestinal tract, digests around 60 metric tons of food
during the average lifespan. Over millennia, the human gut and the huge
colonies of microbes that occupy it have developed a relationship that is both
complex and mutually beneficial.
As
the partnership has evolved, gut microbes have come to play a key role in human
health and disease.
Gut
microorganisms comprise mostly bacteria; they also include fungi, viruses, and
single-celled organisms called protozoa.
Scientists
use the term gut microbiome to refer to the sum of all the genomes of the
trillions of microorganisms in the gut.
The
3 million genes in the gut microbiome vastly outnumber the 23,000 in the human
genome. They also produce thousands of small molecules that carry out many
functions in the human host.
In
this way, gut bacteria help digest food, harvest energy, control immunity, and
protect against pathogens.
However,
imbalances in the gut microbiome can disturb these crucial functions to either
trigger disease or fail to protect against it.
Studies
have linked imbalance in the microbiome to cardiovascular diseases, allergies,
cancer, obesity, and psychiatric conditions.
All nanoparticles bind to gut bacteria
Prof.
Stauber and his colleagues set up experiments in which they could examine the
effects of a wide range of synthetic nanoparticles.
These
experiments simulated the journeys that the different particles might make as
they travel through the different parts of the gut and encounter various
bacteria.
The
main result was that all the “currently used or potential future nanosized
food additives” showed ability to bind to bacteria in the gut.
The
nanoparticles bound to all kinds of bacteria, including the
“probiotic” species that can breed in milk products such as yogurt.
While
all the synthetic nanoparticles that they tested attached to bacteria, the
researchers noticed differences in their binding properties.
When
bound to nanoparticles, the bacteria altered their behavior in some ways that
might prove beneficial and in other ways that might not.
A
potential outcome that could be of benefit is the inhibition of infections, for
example by H. pylori. The team made this discovery when experimenting with
silica nanoparticles in cell cultures.
However,
a potentially disturbing prospect that came up in other experiments was that
binding to nanoparticles could render some unfriendly bacteria less visible to
the immune system. Such a result could increase inflammation responses, for
instance.
An
important point the authors make is that food also contains naturally occurring
nanoparticles — some of which can enter the food during preparation.
The
team also ran experiments on natural nanoparticles and was surprised to find
similar results to the experiments with synthetic nanoparticles.
“It
was puzzling that we were able to also isolate naturally occurring
nanoparticles from food, like beer, which showed similar effects.”
Prof. Roland H. Stauber
SOURCE: MEDICAL NEWS TODAY
Kayode Ojo
Kayode Emmanuel Ojo is the Co-Founder and Managing Director at SHEFFA Limited. He is presently studying Computer Science at the National Open University, Victoria Island, Lagos.